1. Field of the Invention
The present invention relates generally to electric power subsystems for spacecraft and, more particularly, in particular to spacecraft that use electric propulsion thrusters.
2. Discussion of the Related Art
A critical component in spacecraft design is the configuration of the power subsystems that interface the spacecraft primary power and stored power to the spacecraft electronics assemblies. The power subsystems must convert and condition up to tens of kilowatts of power to be distributed to the spacecraft electronics loads and electric propulsion thrusters. Generally, separate spacecraft power components provide conditioned power to the electric thrusters and the spacecraft loads.
Typically, conventional spacecraft include a power bus having a voltage ranging from 20 volts to 50 volts DC for loads up to 5 kilowatts and a voltage range from 50 volts to 100 volts DC for loads above 5 kilowatts.
The electric thrusters can sometimes require up to 20 kilowatts of discharge power at voltages greater than 300 volts DC. To provide discharge power to the thrusters, conventional spacecraft include a power processor unit (PPU) that converts power from the primary power bus. Due to the massive power requirements, the multi-kilowatt PPUs that are used in conventional spacecraft to provide conditioned power to spacecraft electric thrusters are heavy and complex. As a result, the electric thruster PPUs result in significant cost, weight, and reliability penalties for the spacecraft.
While conventional satellite power subsystem configurations can be used to supply power to satellite control electronics and electric thrusters, those configurations have not proven capable of minimizing the potential cost and weight of the associated thruster PPUs.
The present invention provides a satellite power distribution method for efficiently providing power to spacecraft electric propulsion thrusters. The satellite includes a primary energy source, an energy storage source, spacecraft loads, an electric propulsion thruster, thruster auxiliary circuits, a primary energy source controller, and an energy storage controller. The primary energy source controller and the energy storage controller each contain a power transformer. Each power transformer has a primary winding coupled to its energy source that supplies satellite power. A first secondary winding of each power transformer is coupled to the spacecraft loads for supplying primary power. The power distribution method also includes a second secondary winding on each power transformer for converting the satellite power to thruster power which is rectified. The rectified thruster power is filtered to obtain discharge power that is supplied to the electric propulsion thruster. Finally, satellite power is converted to auxiliary power for powering the thruster auxiliary circuits.
For a more complete understanding of the invention, its objects and advantages, reference may be had to the following specification and to the accompanying drawings.